there is a few places in chinatown that sell all those things. there is one at pear'ls centre on 3rd or 2nd level or the one next to OG building second level. I went to the next to OG building second level and ask .... they only tell me when you want to buy we will tell you what to buy which I dun like....
I got mine from Hong Lim Complex 2nd level .... theirs not so fancy looking shop as they are very old shop also selling joss stick and other praying things but they are very nice also teach me wat to do and also give me choices if I want to short cut some other things
Let me know if you interested to go to the one I go I will look for the contacts.